[CentOS] Can anyone talk infrastructure with me?

John R Pierce pierce at hogranch.com
Thu Jan 26 00:50:14 UTC 2012

On 01/25/12 4:27 PM, Jason T. Slack-Moehrle wrote:
> can you explain to the calculation to determine that 300gb is 2mbps?

300GB (big B for byte) / 30 days / 24 hours/day / 3600 seconds/hour, and 
I get 0.12MB/second, so multiplying by 10 to get bits allowing for basic 
protocol overhead, I come up with 1.2Mbit/sec sustained average.

racking 2 PiB (or 2048TiB) of nearline grade storage will require about 
1000 3.5" 3TB drives, allowing for a reasonable raid level and suitable 
number of hotspares.   If its frequently updated transactional database 
storage, I'd want to use raid10.   Using somethign like the Supermicro 
847 chassis, you can get 36 drives plus a server in 4U, and draw about 
700 watts actual in use....  I estimate you'll want about 28 of these 
servers, which will take two full racks and draw about 20KW, or 180 amps 
off 120V household circuits (realistically, you'll need 208V for this 
many servers).   You'll also need about 10-15KW worth of air 
conditioning equipment to deal with the generated 68000 BTUs of heat.   
HVAC will push your power usage up to the 30-40kW range, or 2500 
KWH/month, at $0.20/KWH typical residential power usage, you're looking 
at a $5000/month power bill, give or take.

those 28 SuperMicro servers will cost about $200,000 for the 1000 3TB 
enterprise nearline disks, plus another $200,000 or so for reasonably 
well configured servers.  20KVA of redundant UPS and 70000 BTU worth of 
computer room A/C will add a good chunk more $$$$ to this.

are you serious?

john r pierce                            N 37, W 122
santa cruz ca                         mid-left coast

More information about the CentOS mailing list